Various patents disclose methods and apparatus for forming, filling, and sealing a container. See, for example, U.S. Pat. No. 3,597,793 to Weiler, U.S. Pat. No. 3,919,374 to Komendowski, U.S. Pat. No. 4,176,153 to Weiler et al., U.S. Pat. No. 4,178,976 to Weiler et al., Re. No. 27,155 to Hansen and patents cited therein.
Some of the methods and apparatus disclosed in the above-identified patents employ an extendable and retractable combination blowing and filling assembly. Such an assembly includes a nozzle-like filling tube having means operative on a length of extruded parison of thermoplastic material in a main mold for blow molding the container body portion through a top opening in the parison and for then filling the molded container with a liquid product through the top opening.
A means for controlling flow through a plurality of filling tubes in such apparatus is disclosed in the commonly owned U.S. Pat. No. 4,671,762 to Weiler et al. In the apparatus disclosed in that patent, a liquid product manifold 612 defines a product passageway 622 for supplying the liquid product to a plurality of filling tubes 620. Associated with each filling tube 620 is a diaphragm valve which includes a flexible diaphragm 640 that is normally biased by a spring 644 to close the flow to the associated fill tube 620. All such on-off valves are mounted to a common reciprocating actuation plate 654 so that all of the on-off valves are opened or closed together at the same time. With this actuation mechanism, all of the valves are held open for a predetermined time period to permit a sufficient quality of the liquid product to flow through the filling tubes 620. After the desired quantity of product has been introduced into the containers, all of the on-off valves are closed together at the same time by moving the actuation plate 654 back to the unactuated position.
Although the commercial apparatus discussed above works very well for the applications for which it was designed, it would be desirable to provide an improved apparatus wherein the filling times of the molded containers could be individually controlled. It would also be advantageous if the filling times could be automatically adjusted--preferably from a remote central control system. This would permit the amount of product in each container to be individually regulated without shutting down production. In a typical process for filling a plurality of containers simultaneously, it would then be possible to individually adjust the total flow to each container so that each container could be provided consistently with the same amount of liquid product.
Further, it would be beneficial if such improved apparatus could be provided in the form of a modular filling assembly that could be readily incorporated in existing conventional filling machines.
Other improvements would be desirable as well. Specifically, machines incorporating the apparatus disclosed in the above-discussed U.S. Pat. No. 4,671,762 employ a product metering system in a manner that requires each filling tube 620 to be provided with a separate metering valve 610 for controlling the rate of flow into the container. Each metering valve 610 must be manually adjusted to set the flow rate. When a large number of containers are filled simultaneously, the initial manual adjustment of each associated metering valve 610 is time consuming.
Further, when it is desired to clean the system with sterilizing steam, a sufficient flow of sterilizing steam must be passed through the liquid product flow passages, including the passages defined by filling tubes and associated valves. With the apparatus of the type disclosed in the above-discussed U.S. Pat. No. 4,671,762, the flow rate of sterilizing steam passing through each filling tube depends upon the setting of the associated metering valve 610. In order to ensure that a sufficient flow rate of sterilizing steam passes through the system, each metering valve must be opened a sufficient amount (usually full open) prior to initiating the steam sterilization. This, of course, requires a time-consuming manual adjustment of the metering valves. In view of this, it would be desirable to provide a means for automatically adjusting the flow paths through all of the filling nozzles to accommodate a sufficient flow of sterilizing steam. It would be beneficial if this adjustment could be effected substantially automatically and simultaneously with respect to all of the filling nozzles.